In a separate, rather large bowl, stir together egg whites, mashed bananas, sugar, and oil. Take this and combine it with the flour mixture you have set aside.Stir until moistened, and then spoon batter into the prepared loaf pan.

Bake at 350 degrees for 45 minutes. Cool in the pan on a wire rack for ten minutes. Remove the loaf and cool completely on the rack, or serve warm. If desired, spread butter or margarine on each slice.